Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <iostream>
#include <queue>
using namespace std;

int h, w, b = 0;
char m[51][51];
int d[50][50];
int dx[4] = { 1, 0, -1, 0 }, dy[4] = { 0, 1, 0, -1 };
typedef pair<int, int> P;

int main()
{
	cin >> h >> w;
	
	for (int i = 0; i < h; i++)
		cin >> m[i];

	for (int i = 0; i < h; i++)
		for (int j = 0; j < w; j++) {
			d[i][j] = 0;
			if(m[i][j] == '#')
				b++;
		}

	queue <P> que;

	que.push(P(0, 0));

	while (que.size()) {
		P p = que.front();
		que.pop();

		if (p.first == h - 1 && p.second == w - 1)
			break;

		for (int i = 0; i < 4; i++) {
			int nx = p.first + dx[i],
				ny = p.second + dy[i];

			if (nx > -1 && ny > -1 && nx < h && ny < w 
				&& d[nx][ny] == 0 && m[nx][ny] == '.') {
				que.push(P(nx, ny));
				d[nx][ny] = d[p.first][p.second] + 1;
			}
		}
	}

	if (d[h - 1][w - 1] == 0)
		cout << -1 << endl;
	else
		cout << h * w - b - d[h - 1][w - 1]  - 1 << endl;
	
	return 0;
}